Decreased serotonin activity in the brain is associated with suicide risk.

People who feel hopeless, helpless, or isolated are more likely to consider or attempt suicide.

People who have serious losses -- deaths of close people, loss of jobs, a move -- are more at risk for suicide.

Every 40 seconds, somewhere in the world, someone ends their life.

In the U.S., about 100 people die every day of suicide.

Young people and older adults are more likely to commit suicide.

Guns are the most common method for completed suicide. Poisoning or overdose and asphyxiation/hanging are the next most common methods.

People who have experienced bullying, physical abuse, or sexual trauma are more at risk for considering, attempting, or completing suicide.

Treatment of mental-health conditions can reduce the risk of suicide and improve quality of life.

Suicide Overview

Suicide is most simply defined as the act of intentionally killing one's self. The word suicide may also be used to describe a person who has killed himself. Suicide is often considered a taboo subject, and people often feel uncomfortable discussing it. This sort of stigma may actually prevent individuals from telling others when they are experiencing suicidal thoughts, and it may also prevent people from asking friends and loved ones about suicidal thoughts, even when they may have concerns.

Thoughts of ending a person's own life, or of killing one's self, are also known as suicidal thoughts or suicidal ideation. Some people may plan out suicide attempts, whereas others are impulsive and in the moment.

There are other specific terms used to describe certain types or categories of suicide. Most suicides involve only a single person. Rarely, groups of people, such as members of an extreme religious sect or cult, may commit suicide together -- a mass suicide. An agreement between more than two or more people to commit suicide is a suicide pact. Although these are uncommon, they most often involve a husband and wife or other couple.

When a person first kills another person (or persons) and then ends his or her own life, it is called a murder-suicide. The most common murder-suicide is after a breakup or divorce, when one member of the former couple kills the other and then themselves. Almost all of the perpetrators are men (>90%). Even more rarely, an individual may kill many other people before committing suicide. These cases are very uncommon (less than 0.3 per 100,000 people; <3% of all suicides), but because of the dramatic and horrible loss around these events, they receive a lot of attention and coverage in the news and other media.

Suicide by cop describes a situation when someone commits a crime or threatens someone in an attempt to force police officers to kill him or her. It may be difficult to know for sure what the person intended when they are shot by police. Additionally, an individual's suicide in this way can greatly affect both the police involved as well as the community at large.

Euthanasia should not be confused with suicide. In euthanasia, someone, usually a doctor, makes a decision to actively end someone's life. Most often this is a patient with a terminal illness (an illness that will result in death regardless of treatment) who has been deemed to be unable to make his or her own decisions. Euthanasia is not legal in the United States, but it is considered legal in a few European countries (Belgium, Luxembourg, the Netherlands). In contrast, physician-assisted suicide refers to a doctor prescribing specific medicines that taken together are likely to result in death. Ethically, physician-assisted suicide also requires a person who can make their own decisions, a doctor who will serve this role, and someone who has a life-ending condition. Additionally, assisted suicide (or "assisted dying") is illegal in 46 of 50 states in the United States. Three states have laws permitting assisted suicide (OR, VT, WA) and one state permits assisted suicide based on a court ruling (MT). Internationally, the Netherlands, Belgium, Luxembourg, and Switzerland also allow assisted suicide. A broader discussion of the ethics of euthanasia and assisted death is beyond the scope of this article.

Self-mutilation, such as cutting, burning, or scratching, is deliberate self-harm usually without intending to cause death. Other common methods are hitting the head or other parts of the body, pinching, pulling hair, or picking skin. Although this common behavior is usually not considered suicidal (people usually say they aren't trying to cause death or serious harm), people who self-harm are more likely to eventually attempt suicide or even to eventually end their lives by suicide.

Parasuicide, or parasuicidal behavior, is more difficult to define. Literally, parasuicide means "like" or "near" suicide. This could include suicide attempts in which someone survives, self-mutilation, or suicide attempts in which the method is not expected to cause death.